To install the MPlayer GUI, I need the "libpng and GTK 1.2 development packages". When I run the ./configure command, I get:"Error: The GUI requires GTK ...

GTK+ is a runtime environment that applies to a number of operating systems. If you create an interface for a program, GTK Runtime should be installed on the users’ computers so that the program runs.

The beauty of pyGTK and Glade is they have opened up cross-platform, professional-quality GUI development to those of us who'd rather be doing other things but who still need a GUI on top of it all.